Apparatus for removing an ophthalmic lens from a mold half

ABSTRACT

An apparatus ( 1;2 ) for removing an ophthalmic lens from a mold half ( 3;4 ), comprises a ring member ( 10;20 ) movable towards and away from the mold half ( 3;4 ), the ring member ( 10;20 ) comprising a central opening ( 103;203 ) and a plurality of nozzles ( 100;200 ) circumferentially distributed about the ring member ( 10;20 ), each nozzle ( 100;200 ) having an outlet opening directed towards the mold half ( 3,4 ) as the ring member ( 10;20 ) is placed on the mold half ( 3;4 ), and a gripper member ( 11;21 ) arranged to be movable towards and away from the mold half ( 3:4 ) through the central opening ( 103;203 ) of the ring member ( 10;20 ).

RELATED APPLICATIONS

This application is a Divisional of U.S. patent application Ser. No.12/542,754 filed Aug. 18, 2009, now U.S. Pat. No. 9,254,616, whichclaims benefit under 35 U.S.C. §119 of European Patent Application No.08162663.2, filed on Aug. 20, 2008, the contents of each of which areincorporated herein by reference in their entireties.

FIELD

The present invention relates to a gripper for removing an ophthalmiclens from a mold half. More particular, the invention relates to agripper for removing a contact lens, especially a soft contact lens,from a mold half.

BACKGROUND

In ophthalmic lens production, particularly in contact lens production,and especially in the production of single wear contact lenses, thelenses are produced in a highly automated process. Such processes arewell-known in the art. In one such process, a starting material isdispensed into a female mold half and then the mold is closed with theaid of the corresponding male mold half so as to form a mold cavitybetween the two mold halves. The mold cavity so formed has the shape ofthe contact lens to be produced. The starting material in the moldcavity is then polymerized and/or crosslinked so as to form the contactlens. Subsequently, the mold is opened and the contact lens is removedfrom the mold half to which it adheres for further processing.

The contact lenses are typically removed from the mold half with the aidof a vacuum gripper. However, one of the observations made duringproduction of contact lenses in such a process is that conventionalvacuum grippers are not in all cases capable of reliably removing thelens from the respective mold half. Even if they succeed, it may occurthat a contact lens is damaged due to too high mechanical forces appliedto the contact lens. This holds in particular for, but is not limitedto, contact lenses made from silicon hydrogel materials. Such contactlenses strongly adhere to the mold half.

It is therefore an object of the invention to suggest an apparatus whichallows for reliably removing a contact lens from the mold half and whichavoids damage to the lens due to excess mechanical forces applied to thelens. In particular, such gripper should be capable of removing contactlenses made from silicon hydrogel materials from a mold half. Inaddition, the apparatus should be capable of being used in a highlyautomated production process.

SUMMARY

This object is achieved by the apparatus according to the invention asit is specified by the features of the independent claim. More specificembodiments of the apparatus according to the invention are the subjectof the dependent claims.

In particular, the apparatus for removing an ophthalmic lens from a moldhalf according to the invention comprises a ring member movable towardsand away from the mold half. The ring member comprises a central openingand a plurality of nozzles circumferentially distributed about the ringmember. Each nozzle has an outlet opening directed towards the mold halfas the ring member is placed on the mold half. The apparatus furthercomprises a gripper member arranged to be movable towards and away fromthe mold half through the central opening of the ring member.

Accordingly, the apparatus comprises a nozzle ring member that can beplaced on the mold half and a gripper member that can be moved to aposition directly adjacent to the ophthalmic lens that adheres to themold half. Since the lens may adhere either to the male or to the femalemold half, after opening of the mold it is determined whether the lensadheres to the male mold half or to the female mold half and then thegripper member is moved to the respective mold half to which the lensadheres. Alternatively, nozzle ring members and gripper members areprovided for both the male mold half and the female mold half of a moldand are automatically moved to the male mold half and to the female moldhalf. A fluid such as water or air, can be ejected through the outletopenings of the nozzles so as to loosen the lens from the mold half towhich it adheres. At the same time or even before, vacuum or negativepressure can be applied to the gripper member so as to allow theloosened lens to be suctionally engaged by the gripper member. Afterthat, ejection of the fluid can be terminated while vacuum is stillapplied to the gripper member. The gripper member together with the lenscan then be moved away from the mold half through the central opening ofthe ring member and can subsequently be moved to a lens depositionposition. Having reached the lens deposition position, the suction isreleased and/or positive overpressure can be applied to the grippermember thus releasing the lens from the gripper and depositing it into acontainer, for example, for further processing or packaging.

Such a gripper allows to reliably loosen the lens from the mold half andto transfer it to the gripper member without causing damage to the lensdue to excess mechanical forces applied to the lens. The loosening ofthe lens with the aid of the fluid ejected through the outlet openingsof the nozzles allows the gripper to detach the loosened lens from themold using mild suction without applying excess mechanical forces thatmight damage the lens. Also, the gripper is suitable to be used in ahighly automated process, since all actions to be performed canoptionally be fully automated and controlled with a suitable controlunit.

In one embodiment of the apparatus according to the invention, thegripper member comprises an attachment surface which is provided withholes and a channel which is connected to and is in fluid communicationwith the holes provided in the attachment surface in order to allowsuction or overpressure to be applied for gripping or releasing theophthalmic lens. This is a simple embodiment of a gripper member from aconstructional point of view.

In a further embodiment of the apparatus according to the invention, thering member further comprises a sealing member which is arranged suchthat it provides a seal for the mold halfpreventing fluid from escapingas the ring member is placed on the mold half. This embodiment isadvantageous inasmuch as no fluid is spilled during loosening andremoving the lens.

Since ophthalmic lenses and in particular contact lenses are medicalarticles, in a further embodiment the ring member and the gripper memberare made from a material which is resistant to corrosion, e.g. stainlesssteel or a suitable plastics material. When producing medical articles,such as ophthalmic lenses and in particular contact lenses, it isimportant to maintain clean conditions in the production process so asto avoid contamination of the lenses produced.

Another aspect of the present invention is related to a method forremoving an ophthalmic lens from a mold half. This method comprises thesteps of:

-   -   moving a ring member comprising a central opening and a        plurality of nozzles circumferentially distributed thereabout        towards a mold half carrying an ophthalmic lens, such that the        ring member is placed on the mold half,    -   moving a gripper member towards the mold half through the        central opening of the ring member such that the gripper member        is arranged directly adjacent to the mold half,    -   applying suction through the gripper member,    -   ejecting a fluid through the outlet openings of the nozzles        towards the mold half so as to loosen the ophthalmic lens to        allow it to be suctionally engaged by the gripper member, and    -   moving the gripper member together with the ophthalmic lens away        from the mold half through the central opening of the ring        member.

After the (nozzle) ring member has been placed on the mold half carryingthe ophthalmic lens, suction is applied to the gripper member. However,the suction applied is at least not strong enough to alone remove a lensthat strongly adheres to a mold half, since this may lead to damaging ofthe lens. Rather, a fluid such as water or air is ejected from thenozzles of the ring member so as to loosen the lens adhering to the moldhalf. As the lens has been loosened, the suction causes the lens to begripped by the gripper member. The gripper member together with the lensattached thereto can then be moved away from the mold half through thecentral opening of the ring member. This enables a more gentle and“smooth” but reliable removal of the lens from the mold half even whenmaterials are used which cause the lens to strongly adhere to the moldhalf, such as silicon hydrogel materials.

In a further variant of the method according to the invention, ejectionof the fluid through the outlet openings of the nozzles is terminatedprior to moving the gripper member together with the ophthalmic lensaway from the mold half. This avoids wasting additional fluid after thelens has already been loosened and suctionally engaged by the grippermember.

In a still further variant of the method according to the invention, thegripper member together with the ophthalmic lens is moved towards a lensdeposition position, where the lens is released from the gripper memberby releasing the suction and/or by applying positive overpressurethrough the gripper member. This variant allows the lens to be directlydeposited at a desired location where it can be further processed orpackaged.

In a still further variant of the method according to the invention, thering member is moved away from the mold half after moving the grippermember away from the mold half, but prior to moving the gripper membertowards the deposition position. This variant enables the mold half tobe transported away, e.g. to be cleaned and reused, after the lens hasbeen removed from the mold half. As the next mold half carrying anophthalmic lens is moved so as to be located under the gripper, theprocess can start anew; that is to say, the ring member is placed on themold half, the gripper is moved to be located directly adjacent to themold half, etc. As already mentioned above, the fluid to be ejectedthrough the outlet openings of the nozzles may advantageously be water,however, other suitable fluids are also conceivable (e.g. air, nitrogen,and/or various other liquids and/or gases).

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantageous aspects of the invention will become apparent fromthe following description of preferred embodiments with the aid of thedrawings in which:

FIG. 1 shows an embodiment of an apparatus according to the inventioncomprising a pair of grippers—one male gripper and one female gripper—ina starting position above respective female and male mold halves,

FIG. 2 shows the apparatus of FIG. 1 with the (nozzle) ring members intheir lowermost position placed on the respective mold halves,

FIG. 3 shows the apparatus of FIG. 1 with the (nozzle) ring members andwith the gripper members in their pick-up position (lowermost position),

FIG. 4 shows the gripper members of the apparatus of FIG. 1 above adeposition position, and

FIG. 5 shows the gripper members in the deposition position.

DETAILED DESCRIPTION

In FIG. 1 an embodiment of the apparatus according to the inventioncomprising a pair of grippers 1,2 is shown, the grippers 1,2 beingarranged in the starting position above respective female and male moldhalves. Gripper 1 is a male gripper and comprises a male ring member 10and a male gripper member 11, which are arranged above a female moldhalf 3. Correspondingly, gripper 2 is a female gripper and comprises afemale ring member 20 and a female gripper member 21 which is arrangedabove a male mold half 4.

Both the male ring member 10 and the female ring member 20 are providedwith a plurality of nozzles 100 and 200, respectively (see FIG. 2) whichare distributed about the circumference of the respective male ringmember 10 or female ring member 20, respectively. Each of the nozzles100 and 200 has an outlet opening which is directed towards the femalemold half 3 and the male mold half 4, respectively. The male and femalering members 10 and 20 are provided with sealing member 101 and 201,respectively, which serves for fluid to escape as the ring member 100,20is placed on the respective mold half 3,4, as will become evidentfurther below.

Male gripper member 11 has a convex attachment surface 110 having holes111 therein while female gripper member 21 has a concave attachmentsurface 210 having holes 211 therein. The holes 111 and 211 are adaptedto apply suction (negative pressure) or overpressure (positive pressure)in order to engage and retain an ophthalmic lens such as a contact lensagainst the attachment surface 110 and 210, and to release the lensagain at a later time in the process as will be explained in more detailbelow. Male and female gripper members 11,21 are provided with conduitsor channels 112 and 212, respectively, which are connected to the holes111 and 211 in the respective attachment surfaces 110 and 210, and fluidis delivered through these channels 112 and 212 whereby the suction orthe overpressure can be applied to the holes 111 and 211, respectively.

The male and female ring members 10 and 20 are movable towards and awayfrom the female and male mold halves 3 and 4, respectively, such thatthe ring members 10 and 20 can be placed on the respective female andmale mold halves 3 and 4, respectively. This range of movement of themale and female ring members 10,20 is indicated in FIG. 1 by the doubleheaded arrow MR. Thus, the ring members 10, 20 are movable in a firstdirection (vertically or in the Y-dimension in the depicted embodiments)between a first ring member position that is distal the mold halves 3, 4(shown in example form in FIG. 1), and a second ring member positionthat is proximal the mold halves (shown in example form in FIG. 2).

The male and female ring members 10 and 20 are further provided withcentral openings 103 and 203, respectively (see FIG. 1). The respectivemale and female gripper members 11,21 are movable through these centralopenings 103 and 203 towards and away from the female and male moldhalves 3,4. This range of gripper member movement is indicated in by thedouble headed arrow MG. Thus, the gripper members 11, 21 are movable inthe first direction (coaxially or in parallel alignment with theabove-described motion of the ring members) between a first gripperposition apart from the ring members 10, 20 and apart from the moldhalves 3, 4 (shown in example form in FIGS. 1 and 2), and a secondgripper position extending at least partially through the centralopenings 103, 203 of the ring members and adjacent the mold halves(shown in example form in FIG. 3). In addition, the male and femalegripper members 11,21 are movable towards and away from a depositionposition, in a second direction generally perpendicular or transverse tothe first direction (i.e., horizontally or in the X-dimension in thedepicted embodiments) which is indicated in FIG. 1 by the double headedarrow MD, as will be described in more detail below.

In an example mode of operation of the pair of grippers 1,2, the maleand female ring members 10 and 20 of male and female grippers 1,2 areinitially arranged in the starting position. This position is shown inFIG. 1, where both the male and female ring members 10 and 20 arearranged above the respective female and male mold halves 3,4. The maleand female ring members 10 and 20 are then moved downwardly until theyare placed on or around the respective female and male mold halves 3,4.For the sake of better understanding, let us now assume that anophthalmic lens, e.g. a contact lens (not shown) is adhering to each ofthe male and female mold halves 3,4. In FIG. 2 the male and female ringmembers 10 and 20 are placed on the respective female and male moldhalves 3,4.

The male and female gripper members are then moved downwardly until theyare arranged directly adjacent to the female and male mold halves 3,4 ina pick-up position. This situation, where the male and female ringmembers 10 and 20 are placed on the female and male mold halves 3,4, andwhere further the male and female gripper members 11 and 21 are arrangedin the pick-up position, is shown in FIG. 3. In this position, anegative pressure or suction V (vacuum) is applied to the openings 111and 211 in the attachment surfaces so that the gripper members 11 and 21are capable of sucking the contact lens into engagement against theattachment surfaces. However, at that time the respective contact lensmay still adhere to the respective mold half 3 and 4, respectively. Inorder to loosen the respective lens from the mold half to which itadheres, a fluid such as water W is applied to the respective mold halfthrough the outlet openings of the nozzles 100 and 200 of the ringmembers, respectively. Alternatively, air can be used instead of water.Once a jet or pulse of water has been applied to the mold half and/orthe lens, thereby loosening the lens from the mold half 3,4 to which itadheres, the suction applied through channels 112 and 212 to therespective openings 111 and 211 causes the respective lens to besuctionally engaged against the attachment surfaces 110 and 210 ofgripper members 11 and 21.

Once the respective lens has been suctionally engaged against theattachment surface 110,210 of the respective gripper member 11 and 21,application of the jet or pulse of water through the nozzles 100 and 200is preferably terminated while the application of suction V through thechannels 112 and 212 is preferably continued so as to keep the lensattached to the respective attachment surface. The respective grippermember 11 and 21 is now moved upwardly through the respective centralopening 103 and 203 of the respective ring member 10,20 together withthe lens which is still attached to the attachment surface 110,210 ofthe respective gripper member 11,21. The corresponding ring member 10,20is then moved upwardly back to its respective starting position, so thatthe ring members 10,20 and the gripper members 11,21 are in theirstarting position again (see FIG. 1). It is to be mentioned, however,that the lens still adheres to the attachment surface of the respectivegripper member 11,21 due to the continued application of suction Vand/or by surface tension or adhesion.

Since the ring members 10,20 have also been raised back to theirstarting position, the “empty” mold halves 3,4 can be transported awayfrom the position underneath the grippers 1,2, so that they can becleaned and reused, for example. Also, the next mold halves carryinglenses can then be moved into position underneath the grippers 1,2 forsequential processing. After the lenses presently attached to thegripper members 11,21 have been deposited, the process cycle can startanew. The step of depositing the lens will be explained in more detailbelow.

As mentioned further above, the gripper member together with lensattached thereto can be moved towards a deposition position. Thismovement is indicated in FIG. 1 and in FIG. 2 by arrow MD. The grippermembers 11,21 with the lens attached thereto are shown in FIG. 4 in theposition where deposition is to occur, with the gripper members 11,21still being in the raised position. In order to deposit the respectivelens in a container (or on a carrier) which may be a female or malecontainer 5,6 (or a female or male lens carrier), the gripper members11,21 are moved downwardly to the deposition position shown in FIG. 5,in which they are arranged directly adjacent the respective container5,6 (or carrier). This possible movement is indicated by thedouble-headed arrow LD. At this point of time, suction V is terminatedand/or overpressure P is applied via delivery of a suitable fluid (e.g.air or water) through openings 111, 211 via the fluid conduits orchannels 112, 212 so as to release the lens from the attachment surfacesof the respective gripper member 11,21 and to insert it into or onto therespective container or carrier for further processing.

The gripper members 11,21 can then be raised again and moved back totheir initial starting position (see FIG. 1) and the described cycle canthen start anew. The various components of the grippers 1,2 arepreferably made from a material which is resistant to corrosion, e.g.they are made from stainless steel or from a suitable plastics material.In example embodiments, the pressure with which water is applied throughthe outlet openings of the nozzles 100,200 in order to loosen the lensmay be in the range of 1 to 4 bar, while the overpressure P of the fluidfor releasing the lens from the gripper members 11,21 may be in therange of from 0.2 to 1 bar.

As has been mentioned above, the grippers 1,2 can be advantageously usedin a highly automated process for producing contact lenses in order toautomatically remove the lenses from the mold halves, even if theselenses are made from a material such as silicon hydrogels which tend tostrongly adhere to the mold halves.

While the invention has been described with reference to preferred andexample embodiments, it will be understood by those skilled in the artthat a variety of modifications, additions and deletions are within thescope of the invention, as defined by the following claims.

The invention claimed is:
 1. An apparatus configured to remove anophthalmic lens from a mold half, comprising: a ring member configuredto be movable towards and away from the mold half, the ring membercomprising a central opening and a plurality of nozzlescircumferentially distributed about the ring member, each nozzle havingan outlet opening directed towards the mold half as the ring member isplaced on the mold half, and wherein the ring member further comprises asealing member configured to provide a seal for the mold half preventingfluid from escaping as the ring member is placed on the mold half; and agripper member configured to be movable towards and away from the moldhalf through the central opening of the ring member.
 2. The apparatusaccording to claim 1, wherein the gripper member comprises an attachmentsurface which is provided with holes and a channel which is connected toand in fluid communication with the holes provided in the attachmentsurface configured to allow suction or overpressure to be applied forgripping or releasing the ophthalmic lens.
 3. The apparatus according toclaim 1, wherein the ring member and the gripper member are made from amaterial which is resistant to corrosion, e.g. comprising stainlesssteel or plastic material.